The Barton Creek greenbelt runs through Austin, Texas and is known for the beauty of its crystal clear waters and wooded banks. Off the trail and set back in the thick woods, this rock fence is easy to overlook. To this day the identity of the builders remains a mystery. There are no records of pioneers in the Austin area constructing the enclosure and some say early Spanish explorers built it, but no definitive proof has put the mystery to rest. It's likely there will be no resolution of the question and that makes the fence an interesting site to visit and contemplate the distant past.